Nematodes (nema--threads; oides--resembling) are unsegmented roundworms with elongated, fusiform or saclike bodies covered with cuticle which belong to the phylum Nemathelminthes and are virtually ubiquitous in nature, inhabiting soil, water and plants. The effects of what are now known as plant-pathogenic species of nematodes have been recognized since biblical times and continue to be major causes of crop losses worldwide. In 1982, by way of example, crop losses due to nematodes in the U.S. alone were estimated to exceed $5 billion, reflecting losses in farm production of 42 million tons of field crops, 5 million tons of vegetable and melon crops and 4 million tons of fruit and nut crops. Nematodes were also estimated to cause 10 percent or more losses in the economic value of floral crops, lawns and turf, and ornamentals.
Man has added organic and inorganic amendments to soil for centuries to improve soil fertility and increase crop yield. The nematicidal effects of some of these amendments have been recognized for some time and reviews on the subject have been published; e.g., R. Rodriguez-Kabana, J. Nematol. 18:129-135 (1986) and R. Rodriguez-Kabana, G. Morgan-Jones and I. Chet, Plant and Soil, 100:237-247 (1987), the contents of which are incorporated by reference herein. Particularly noteworthy is page 239 of this article, which discloses that organic soil amendments are nematicidal when the C:N ratio is less than 20, but the amendments are phytotoxic when the C:N ratio drops below 11.
While most nematicidal soil amendments are oil-cakes and meals or manures and composts, it has also been found that some organic nitrogenous amendments, especially those with low carbon:nitrogen (C:N) ratios and high "protein" contents as measured by Kjeldahl nitrogen methods, act when added in quantity to soils as if they were toxins for nematodes. Most interesting among these organic nitrogenous amendments for control of plant-pathogenic soil nematodes are materials which contain ammoniacal nitrogen, such as urea (e.g., see J. T. Walker, J. Nematology, 3:43-49 (1971)) and materials which contain chitin and related mucopolysaccharides (e.g., see M. B. Linford, F. Yap and J. M. Oliviera, Soil Science, 45:127-141 (1938); R. Mitchell and M. Alexander, Plant Dis. Reporter, 45:487 (July 15, 1961); Soil Sc. Soc., 26:556-558 (1962); I. H. Mian, G. Godoy, R. A. Shelby, R. Rodriguez-Kabana and G. Morgan-Jones, Nematropica 12:71-84 (1982); G. Godoy, R. Rodriguez-Kabana, R. A. Shelby and G. Morgan-Jones, Nematropica 13:63-74 (1983); R. Rodriguez-Kabana, G. Morgan-Jones and B. Ownley Gintis, Nematropica, 14:10-25 (1984) and A. K. Culbreath, R. Rodriguez-Kabana and G. Morgan-Jones, Nematropica, 16:153-166 (1986). See also McCandliss, Eastwood and Milch, U.S. Pat. No. 4,536,207). J. T. Walker, J. Nematology, 1:260-264 (1969) studied the nematicidal effects of soil amendments with soybean meal and of soil amendments with urea, but this reference does not discuss soil amendments with both urea and soybean meal.
Urea has been demonstrated to be a good nematicide at high application rates (e.g., .gtoreq.300 mg N/kg soil) but it is also phytotoxic at these levels owing to its low C:N ratio. Detrimental effects of high soil concentrations of urea can be overcome, however, by supplementing urea amendments with additional available carbon required to ensure adequate stimulation in soils of microbial metabolic activity (See, for example: Huebner Dissertation: Hemicellulosic Waste and Urea for Control of Plant Parasitic Nematodes, Order No. DA8212687, Auburn University (1982), Chemistry Abstracts, 97:67774b; R. Rodriguez-Kabana and P. S. King, Nematropica, 10:38-44 (1980); and R. A. Huebner, R. Rodriguez-Kabana and R. M. Patterson, Nematropica, 13:37-54 (1983).
It is known to prepare a fertilizer by combining urea with soybean meal (see, e.g., Keyssner et. al., U.S. Pat. No. 1,857,914 and Baskin, U.S. Pat. No. 3,558,299), Mortenson et. al., U.S. Pat. No. 2,827,368 mention soybean meal and urea as fertilizers but does not mention combining the two. Stoller, U.S. Pat. No. re.22,202 lists both soybean meal and urea as examples of nitrogen sources for a compost for mushroom culture, but Stoller does not teach the combination of the two. Reynolds et. al., U.S. Pat. No. 3,249,441 utilizes a soybean meal and urea combination for animal feed. Other agriculturally derived ingredients have been combined with urea as fertilizer or for other culturing compositions (see, e.g., Stoller, U.S. Pat. No. 2,260,201 (with cottonseed meal for mushroom culture) Tellier et. al., U.S. Pat. No. 4,401,762 (with corn cob extract for culturing microorganisms); Tellier et al, U.S. Pat. No. 4,460,692 (with corn cob extract for culturing microorganisms). Wagner et al, U.S. Pat. No. 4,283,219 combines fish-meal or bone-meal with urea for fertilizer. Soy lecithin has been combined with urea for use in depolluting water through microbial action (Olivieri et al, U.S. Pat. No. 4,414,333).
Soybean meal compositions have been disclosed for use in the control of nematodes, but these references do not teach the use of urea in combination with soybean meal (see. e.g. Walker, supra; Kodama et al U.S. Pat. No. 3,660,571; McBrayer. U.S. Pat. No. 4,442,092 (sesame meal instead of soybean meal); Carlile et al, U.S. Pat. No. 434,243 (cottonseed meal instead of soybean meal; control of insects and cut-worm instead of nematodes); McCandliss et al, U.S. Pat. No. 4,536,207 (shellfish waste instead of soybean meal)).
As ancillary background information, it should be noted that until quite recently the high cost of producing chitin and chitin derivatives in commercial quantities has effectively eliminated any practical or commercial uses of the polymer in either horticulture or agriculture. McCandliss et al., U.S. Pat. No. 4,536,207, issued Aug. 20, 1985, describes a low cost process for manufacturing a chitin-protein complex with demonstrable nematistatic and nematicidal activity, marketed by IGENE Biotechnology, Inc. of Columbia, Md. under the registered trademark ClandoSanR.RTM., which provides a commercially useful chitin product for application in both horticulture and agriculture. As with other nitrogenous soil amendments, chitin soil amendments have also been found to be phytotoxic at high concentrations.
Finally, it should be noted that increasing governmental restrictions, both in the United States and abroad, against the use of highly effective but environmentally hazardous and toxic synthetic agrichemicals, such as ethylene dibromide (EDB), dibromochloropropane (DBCP) and possibly other halogenated hydrocarbon compounds as well as numerous carbamates and organophosphates, demonstrate the need for active compositions and formulations of matter which have significant nematicidal effects against commercially important plant-pathogenic nematodes, avoid phytotoxic effects and provide excellent plant nutrition at cost and price structures which make the products competitive with currently used synthetic pesticides. The present invention fills such a need.